Promotion of ethylene/isoparaffin alkylation

ABSTRACT

The rate of ethylene alkylation by isobutane can be promoted by carrying out the reaction simultaneously with the alkylation of a small amount of a higher weight olefin by isobutane; low temperatures and pressures using a BF3.H3PO4 complex as the catalyst, are employed.

United States Patent Hoffman PROMOTION OF ETHYLENE/ISOPARAF FINALKYLATION [75] Inventor: David M. Hoffman, Weston, Conn.

[73] Assignee: Sun Ventures, Inc., St. Davids, Pa.

[22] Filed: Oct. 17, 1973 [211 App]. No.: 407,398

Related [1.8. Application Data [63] Continuation-impart of Ser. No.257.090, May 26,

UNITED STATES PATENTS 2,363,222 11/1944 Beyerstedt ..260/683.44

[ Mar. 25, 1975 6/1946 Schulze et al 260/683.44 7/1946 Axe 260/683,.44

Primary Examiner-Delbert E. Gantz Assistant Examiner-G. J. CrasanakisAttorney, Agent, or Firm-George L. Church; Donald R. Johnson; StanfordM. Back [5 7] ABSTRACT The rate of ethylene alkylation by isobutane canbe promoted by carrying out the reaction simultaneously with thealkylation of a small amount of a higher weight olefin by isobutane; lowtemperatures and pressures using a BF .H PO complex as the catalyst, areemployed.

16 Claims, No Drawings PROMOTION OF ETHYLENE/ISOPARAFF IN ALKYLATIONCROSS-REFERENCE TO RELATED APPLICATION This application is acontinuation-in-part of U.S. Ser. No. 257,090 filed May 26, 1972 byDavid M. Hoffman.

BACKGROUND OF THE INVENTION This invention relates to an improvedprocess for the alkylation of a C or C monoolefin with a C C,isoparaffin in the presence of a BF H PO, catalyst. More particularly,this invention relates to an improved method of alkylating ethylene orpropylene by the aforesaid paraffins by carrying out the reactionsimultaneously with the alkylation of a small amount of a highermolecular weight monoolefin by said isoparaffin.

The alkylation of ethylene with isobutane using a BF H PO, complex asthe catalyst is already known in the art. These methods, while they doproduce some of the desired alkylate, are nevertheless characterized byrelatively low yields and slow reaction rates.

U.S. Pat. No. 2,401,884 teaches the alkylation of higher olefins withisoparaffin, using an H PO BF catalyst, wherein said catalyst is firstpreheated or conditioned with small amounts ofa lower molecular weightolefin in order to stabalize this BF catalyst. This latter olefin,preferably ethylene, may be included in small amounts in the feed streamwith the higher olefin which is to be alkylated. However, a means forimproving the rate of alkylation of ethylene or propylene withisoparaffins is neither taught nor suggested by this patent.

SUMMARY OF THE INVENTION In accordance with the present invention, ithas now been found that C or C monoolefins may be alkylated by C -Cisoparaffins with marked increases in yields and rates when the reactionis carried out simultaneously, i.e. in combination with, the alkylationof a small amount of a different, higher molecular weight monoolefin bysaid isoparaffins, and when the catalyst employed is a 8P H PO, complex.Thus, for example, the alkylation of ethylene by isobutanesimultaneously with the alkylation of butene-2 to form an alkylatecontaining large amounts of 2,3-dimethylbutane represents one preferredembodiment, but other alkylations such as the alkylation of propylene byisobutane in the presence of butylene may likewise be satisfactorilyachieved in accordance with this novel process. The resulting alkylatemixtures comprising C C isoparaffins, particularly 2,3-dimethylbutaneand trimethylpentanes, are useful as components in motor fuels.

DESCRIPTION OF THE INVENTION The reaction may conveniently be carriedout using known alkylation methods and suitable apparatus attemperatures of from about -l0 to 50C, preferably 0 to C, and atpressures of from about 1 to 1,000 psi, depending upon the reactantsemployed, for periods of from about 0.05 to 1 hour. Although none ofthese parameters is particularly critical, it will be noted thatadvantageously and desirably the reaction is carried out at temperaturesand presssures substantially below those ranges employed by theabove-described prior art.

The principal monoolefin reactant to be alkylated is, as aforestated,preferably ethylene, although propylene may also be employed. Mixturesof these two olefins, or mixtures of these olefins with C -C paraffins,as for example a refinery stream boiling at less than 20C may also beused. In the case where such a mixture of light olefins containing largeamounts of paraffins is used as the charge stock, not only do theparaffins not interfere with the reaction but actually the reactionserves as one convenient way of separating the olefins from theseparaffins. In such a process the light olefins are alkylated to form a Cand heavier alkylate from which any unreacted ethane, propane andn-butane are easily separated by distillation.

Although the preferred isoparaffin reactant is isobutane, it will beunderstood that any C -C paraffin or mixture thereof, having at leastone tertiary carbon atom, may be employed in this process, as forexample isopentane, methylcyclopentane or the like. The molar ratio ofisoparaffin to ethylene or propylene should desirably be in the range of1:1 to 100: 1, and preferably 10:1, in order to maintain a large excessof isoparaffin over the ethylene or propylene.

The other monoolefin which acts as a promoter for the alkylation of theethylene by simultaneously alkylating it with the isoparaffin, togetherwith the principal monoolefin, i.e. the ethylene or propylene must, ofcourse, be a different olefin, and should be a higher molecular weightmonoolefin in the C -C range. Included amongst these monoolefins, whichserve to promote the alkylation reaction between the isoparaffin andfirst monoolefin, are propylene, butene-l,butene- 2, isobutylene,2-methylbutine-2 and mixtures thereof, particularly mixtures comprisingbutene-l, butene-2 and isobutylene.

Although propylene can serve as the second monoolefin for purposes ofaccelerating the rate of ethylene alkylation, its own alkylation ratecan also be accelerated by simultaneously alkylating it in the presenceof a C, or higher olefin. It will be understood, as stated above withrespect to the first monoolefin, that mixtures of the C -C monoolefins,or mixtures of these olefins with normal paraffins, perferably in the CC range, may also be employed. The molar ratio of the ethylene orpropylene to the higher weight C to C monoolefin should desirably be atleast 5:1, and preferably 10-2011, in order to maintain a substantialexcess of ethylene or propylene over the C to C olefin at all times.

It will thus be understood from the foregoing that the amount of C to Colefin used will always be much smaller than the amount of ethylene ofpropylene employed, since more amounts of C to C olefin have been foundunexpectedly, to serve as a promoter for the alkylation of ethylene.That is to say, the second olefin is not there for the principal purposeof being alkylated to form alkylate: it is only added for the purpose ofincreasing ethylene alkylation. Thus, although the second olefin ispresent in considerable smaller proportions than the ethylene, itspresence causes a much larger number of moles of ethylene to bealkylated than the number of moles of higher olefin present, therebydemonstrating an unexpected catalyst-like role.

The BF;,. H PO, complex used as the catalyst for the novel process ofthis invention may be prepared in one or more ways, as described in U.S.Pat. No. 2,363,222 (supra). Thus, in one such method, a commercial gradeof orthophosphoric acid ranging from about 60 to percent, with theremainder water, is contacted with E1 gas by bubbling the gas throughthe acid solution until there is no further change in weight of thesolution. The resulting solution then comprises the BP H P catalyst.

Alternatively, the aforedescribed 85 percent orthophosphoric acid may befirst contacted with sufficient P 0 to form the equivalent of 100percent orthosphosphoric acid. To this composition is then addedsufficient BF again by bubbling it through the solution until no moreBFj; is taken up, to form the BF H PO complex. The amount of saidcatalyst employed in this process is generally about to 500 ccs per 100cc of isoparaffin, and preferably 75 to 150 cc.

In the following examples, Example 1 illustrates the prior art methodwhere ethylene and isobutane alone are alkylated. In Example 2, acomparative run where butene-2 is alkylated by isobutane in the absenceof ethylene is also provided, together with one run (three samples) inaccordance with the process of this invention. Examples 3 to 6 arelikewise in accordance with the instant invention. When the results ofExamples 3 to 6 are compared with the results in Examples 1 and 2, itwill be very evident that a substantial increase in yields and rates isachieved over the prior art methods while at the same time employing thelower temperatures and pressures.

In each of the following examples run in accordance with the presentprocess, the rate of introduction of the two different olefms wascontrolled in order to provide and continuously maintain, a substantialexcess of ethylene of propylene over the C olefin within theaforedescribed parameters. This was achieved principally by maintaininga substantially fixed ethylene pressure and adding the butane compoundslowly during the course of the reaction. That is to say, as long asexcess pressure of ethylene or propylene is maintained, and the secondolefin is fed slowly into the reaction zone, the mole ratio of principalolefin to second olefin remains high because the rate of alkylation ofthe second olefin is very fast and its concentration is always low inthe reaction zone.

EXAMPLE 1 200 cc of H PO 100%).BF was emulsified with 200 cc ofisobutane in a l-liter stirred Parr reactor at 10C while 60 to 80 psipressure was maintained with ethylene. Samples were taken at 60 minuteintervals and analyzed vs. an internal standard of n-octane with thefollowing results:

Butene-2 (23.6g) in 75 cc of isobutane was added to an emulsion of 200cc H PO (100%).BF and 150 cc of isobutane at 10C over a period of 48minutes. During the entire reaction the pressure maintained between 60 4to psi with ethylene. The alkylate was sampled at 55, 75 and 105 minutesafter the start of butene addtion. A minute butene-2 alkylation withoutethylene is given for comparison.

TIME 55 Min. 75 Min. Min. 100 Min.

Ethylene Pressure (psi) 60-80 6080 60-80 0 Alkylate Yield 88.5 96.3112.7 46.9

(g) Product Composition 1C 5.8 5.3 4.7 5.7 2,3-DMB 2MP 29.8 30.6 29.33.1 3MP 1.3 1.2 1.0 0.5 C 5.6 5.8 6.4 4.4 TMPs 30.3 29.2 27.8 64. DMH 's9.6 10.2 11.9 8.5 C 17.6 17.4 18.9 12.6

The above reactions were carried out at 5C and 20C with comparableresults.

The data in these two examples indicate that during the addition ofbutene-2, the amount of alkylate formed is much greater than that formedseparately by isobutane/ethylene and isobutane/butene-Z alkylation underthe same conditions. Moreover, the increase in the alkylate is caused byan increase in the product that results from the alkylation of ehtylenewith isobutane (Le. large amounts of 2,3-dimethylbutane are formed).

EXAMPLE 3 2-methylbutene-2 (22.0 g) in 60 cc of isobutane was added toan emulsion of 200 cc H PO (100 percent).BF and 140 cc of isobutane at10C over a period of 38 minutes. During the entire reaction the pressurewas maintained at between 60 to 80 psi with ethylene. The alkylate wassampled at 48 and 78 minutes after the start of olefin addition.

200 cc of H PO BF H O prepared by saturating 90 percent H PO with B1 wascombined with cc of isobutane in a l-liter monel stirred reactor. Thepressure was maintained'at 608O psi with ethylene as 22.5 g of butene-1in 75 cc of isobutane was added over 40 minutes while maintaining thetemperature at 10C. The alkylate was analyzed 50 and 70 minutes afterthe butene-l addition was started. Ethylene pressure was maintainedthroughout the entire sampling period.

Time 50 Minutes 70 Minutes Alkylate Yield (g) 44.8 46.1

(Wt%) 199 205 Product Composition (Wt%) iC 4.3 3.7 2,3-DMB 24.4 25.0 2MP3MP 3.5 3.5 1 2.8 2.7 TMPs 33.9 33.8 DMHX'S 17.4 17.4 C 13.5 13.4

EXAMPLE 5 A mixture of 200 cc of H PO 100 percent).BF and 125 cc ofisobutane was emulsified in a 1-liter Parr reactor at C. A mixture of4.0 g isobutylene, 10.3 g butene-1 and 7.9 g propylene in 75 cc ofisobutane was fed to the reaction simutaneously with 8.1 g of ethyleneover a period of 52 minutes. The alkylate was analyzed 10, 30 and 50minutes following the completion of the olefin addition.

Time following addition Yicld* (Wt /I) Product Composition (WW1) Yieldbased on total C -C olefin charged.

In accordance with the foregoing procedure, but adding butene-Z to themixture of isobutylene and butene- 1, there is obtained a like alkylateproduct mixture in the C C range.

EXAMPLE 6 TIME Minutes 40 Minutes Yield (wt.% on iC 300 327 Composition(wt.%)

6 iC 8.4 7.6 2.3-DMB 2MP 33.5 34.8 3MP 0.7 0.7 C 's 6.4 6.2 TMP's 23.522.8 DMH s 7.9 8.5 C 19.3 19.3

The invention claimed is: 1. In the process for the alkylation of afirst monoole- 10 fin comprising ethylene or propylene by C.,-Cisoparaffins in the presence of BF H PO catalyst, the improvementwherein said alkylation is carried out simultaneously with thealkylation of said isoparaffin by a second, different monoolefin havinffrom 3 to 8 carbon atoms, wherein the mole ratio of first monoolefin tosecond monoolefin is at least 5:1.

2. The process according to claim 1 wherein the first monoolefin isadmixed with normal paraffins having from 2 to 4 carbon atoms.

3. The process according to claim 1 wherein the second monoolefin isbutene-l.

4. The process according to claim 1 wherein the second monoolefin isbutene-Z.

5. The process according to claim 1 wherein the second monoolefin is2-methylbutene-2.

6. The process according to claim 1 wherein the second monoolefin isisobutylene.

7. The process according to claim 1 wherein the second monoolefin is amixture comprising butene-l, butene-2 and isobutylene.

8. The process according to claim 1 wherein the second monoolefin isadmixed with normal paraffins having from 2 to 4 carbon atoms.

9. The process according to claim 1 wherein the iso paraffin isisobutene.

10. The process according to claim 1 wherein the alkylation is carriedout at a temperature of from about -10 to 50C.

11. The process according to claim 1 wherein the reaction is carried outunder pressure in the range of about 1 to 1,000 psi.

12. The process according to claim 1 wherein the molar ratio ofisoparaffin to first monoolefin is from about 1:1 to :1.

13. The process according to claim 1 wherein the mole ratio of firstmonoolefin to second monoolefin is in the range of from about 10:1 to20:1.

14. The process according to claim 1 wherein the ratio of isoparaffin tocatalyst is from about 10 to 500 cc to catalyst per 100 cc ofisoparaffin.

15. The process according to claim 1 wherein the first monoolefin isethylene, the isoparaffin is isobutane and the second monoolefin isbutene-2.

16. The process according to claim 1 wherein the first monoolefin isethylene, the isoparaffin is isobutene, and the second monoolefin is amixture of olefins comprising butene-l, butene-2 and isobutylene.

1. IN THE PROCESS FOR THE ALKYLATION OF A FIRST MONOOLEFIN COMPRISINGETHYLENE OR PROPYLENE BY C4-C8 ISOPARAFFINS IN THE PRESENCE OF BF3.H3P04 CATALYST, THE IMPROVEMENT WHEREIN SAID ALKYLATION IS CARRIED OUTSIMULTANEOUSLY WITH THE ALKYLATION OF SAID ISOPARAFFINS BY A SECOND,DIFFERENT MONOOLEFIN HAVING FROM 3 TO 8 CARBON ATOMS, WHEREIN THE MOLERATIO OF FIRST MONOOLEFING TO SECOND MONOOLEFIN IS AT LEAST 5:1.
 2. Theprocess according to claim 1 wherein the first monoolefin is admixedwith normal paraffins having from 2 to 4 carbon atoms.
 3. The processaccording to claim 1 wherein the second monoolefin is butene-1.
 4. Theprocess according to claim 1 wherein the second monoolefin is butene-2.5. The process according to claim 1 wherein the second monoolefin is2-methylbutene-2.
 6. The process according to claim 1 wherein the secondmonoolefin is isobutylene.
 7. The process according to claim 1 whereinthe second monoolefin is a mixture comprising butene-1, butene-2 andisobutylene.
 8. The process according to claim 1 wherein the secondmonoolefin is admixed with normal paraffins having from 2 to 4 carbonatoms.
 9. The process according to claim 1 wherein the isoparaffin isisobutene.
 10. The process according to claim 1 wherein the alkylationis carried out at a temperature of from about -10* to 50*C.
 11. Theprocess according to claim 1 wherein the reaction is carried out underpressure in the range of about 1 to 1,000 psi.
 12. The process accordingto claim 1 wherein the molar ratio of isoparaffin to first monoolefin isfrom about 1:1 to 100:1.
 13. The process according to claim 1 whereinthe mole ratio of first monoolefin to second monoolefin is in the rangeof from about 10:1 to 20:1.
 14. The process according to claim 1 whereinthe ratio of isoparaffin to catalyst is from about 10 to 500 cc tocatalyst per 100 cc of isoparaffin.
 15. The process according to claim 1wherein the first monoolefin is ethylene, the isoparaffin is isobutaneand the second monoolefin is butene-2.
 16. The process according toclaim 1 wherein the first monoolefin is ethylene, the isoparaffin isisobutene, and the second monoolefin is a mixture of olefins comprisingbutene-1, butene-2 and isobutylene.